General Avian Flu Facts
There are two types of avian flu, highly pathogenic avian influenza (HPAI), and low pathogenic avian influenza (LPAI).
Low pathogenic avian influenza produces a mild disease that commonly goes undetected in birds. Low pathogenic avian flu is not a threat to birds or humans.
Highly pathogenic avian flu is what scientists are really concerned about. This type of avian flu produces a deadly disease that kills quickly, and causes epidemics among birds. There is a death rate of 90% in infected birds, and 50% in humans.
Where virus infects
Like regular human influenza, avian flu infects the epithelial cells lining the respiratory tract (throat) and in the lungs.
Highly pathogenic avian flu infection is not limited to the lungs. The virus soon spreads throughout the body, infecting many other organs. Organs that the virus usually spreads to include the heart, brain, and intestines. While the virus spreads to other parts of the body, infection in the lungs still continues; the lungs are where the virus primarily replicates.
Picture of several symptoms of avian flu in birds.
Picture courtesy of Ministry of Agriculture, Thailand.
Symptoms in Birds
Mild avian flu in domestic birds often goes undetected. It produces little or no symptoms. Symptoms can include ruffled feathers and slower egg production.
Domestic birds with highly pathogenic avian flu first develop mild symptoms, like those of low pathogenic avian flu. As the disease progresses, and the virus spreads to other organs, much more severe symptoms develop, including
- breathing difficulties
- swollen head
Sometimes, birds die on the same day symptoms appear.
On the other hand, migratory waterfowl can harbor avian flu viruses without getting sick, or developing any symptoms.
s in Humans
Initially, symptoms in humans are similar to normal human influenza symptoms, like
- sore throat
- muscle aches
People infected with highly pathogenic avian flu eventually develop serious complications as the disease progresses and spreads throughout the body, such as
- eye infections
- acute respiratory distress
- inflammation of the brain and heart.